Objectives: The role of the viridans group ot" streptococci [Streptococcus oralis) in the prevention of colonization with
Streptococcus pneumoniae was investigated in an adenoid organ culture system.
Methods: The adenoids from 10 patients who were undergoing adenoidectomy for either hypertrophy or recurrent otitis
media were used.
Results: Streptococcus oralis Parker and S oralis Booth (two organisms isolated from the nasopharyngcs ot patients undergoing
adenoidectomy only and patients undergoing adenoidectomy and bilateral tympanostomy with tubes, respectively)
uniformly inhibited both penicillin-sensitive and penicillin-resistant S/J/JC/^/HWI/V/C. Although both strains of .Sor«/),sinhibited
the growth of both S pneumoniae strains, strain Parker provided mure complete inhibition than did striiin Booth.
Conclusions: The results indicate that some strains of S oralis may inhibit the growth of the most serious pathogens in
the nasopharynx. It is therefore possible that colonization of inhibitory strains of viridans streptococci may be used in the
nasopharynx as a relatively safe and ine.xpensive approach to prevention of recurrent otitis media in some children and of
recurrent suppurative sinusitis in both children and adults.
Key Words: adenoid, bacterial interference. Streptococcus oralis. Streptococcus pneumoniae.